Electric clock



(No Model.)

P. R. FIELD.

ELECTRIC CLOCK.

No. 324,824. Patented Aug. 25, 1885.

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N. PETERS, PhntmLnhogmphen Washmgicn. u. c.

NITED STATES PATENT Felon.

FRANK R. FIELD, OF GREENFIELD, MASSACHUSETTS.

ELECTRiC CLOCK.

SPECIFICATION forming part of Letters Patent No. 324,824, dated August 25, 1885.

Application filed June 1, 1885 To ctZZ whom it may concern:

Be it known that I, FRANK R. FIELD, of Greenfield, Franklin county, State of Massachusetts, have invented an Improvement in Electric Clocks, of which the following description, in connection with the accompany ing drawings, is a specification, like letters on the drawings representing like parts.

My invention relates to an electric clock of that class in which an electro-magnct is employed to store power that is applied to a time measuring pendulum, so as to maintain the oscillation of the pendulum, which in turn controls the circuit of the electro magnet, changing its condition at each beat of the pendulum, so that the power of the said magnet may also be employed to turn the hands of the clock, or, in other words, count or indicate the number of beats of the pendulum, and the clock may also,through a suitable elec tric circuit, control other secondary clocks, maintaining them in unison with the main or primary clock.

The invention consists, mainly, in novel details of construction and arrangement of the electro-magnet and pendulum, and intermediate mechanism by which the one controls or affects the operation of the other. As shown, in this instance two electro-magnets are employed, being called into action alternately at the tooand-fro vibrations of the pendulum, and the said magnets are preferably of the kind known as differential magnets, having two separate coils so related to one another that when the current is passing through both coils the effect on the core of the magnet is neutralized,-but when the current passes through one only of the said coils the cores are magnetized, and the magnet produces its maximum attractive effect. This kind of magnet is preferred, as it diminishes or annuls the sparks that would otherwise be produced at the circuit closer and breaker controlled by the pendulum. The two magnets act alternatively to vibrate a single armature lever in opposite directions on its pivot, and the said armature-lever is provided with a fork or two projections, which receive between them the free end of a spring connected with the pendulum-rod. The said spring and the projec- (No model.)

of the magnets, and are so arranged that when the pendulum arrives near the end of its oscillation in one direction it reverses the actuating-current from one to the other of the said magnets in such manner that the armaturelever and fork are tilted so as to press against and strain the spring, bringing its elastic force into action to move or impel the pendir lum in the other direction, at the end of which movement the condition is reversed and a similar impulse produced in the opposite direction, this impulse being sufficient to overcome the usual resistance to the movement of the pendulum, and thus maintain it steadily in vibration. The impulse on the pendulum does not depend upon the force exerted by the magnet on the armaturelever, which is always greater than required to strain the impellingspring,which thus transmits a definite amount of the said force only derived from its own elasticity to the pendulum at each movement. The armature-lever also actuates the hands of the clock, advancing them a definite amount at each movement, so that the movement of the hands depends upon the ti memeasuring pendulum, as in other clocks.

Figure 1 is an elevation of the clock mechanism as seen looking toward the dial, the frame-work and hands of the clock being removed and the circuits being shown in dia gram; Fig. 2, a side elevation of the clock mechanism, and Fig. 3 a rear elevation of the actuating mechanism of the secondary clock, the circuit-connection between which and the main or primary clock shown in Fig. 2 being indicated in diagram.

The main clock contains a pendulum-bob, a, (see Fig. 1,) supported on a rod, a, adapted to oscillate about a point of support in any usual manner, being, as shown in this instance, hung upon a slender spring, a

The pendulum and its rod may be constructed in any approved manner to compensate for changes in temperature, so that its oscillations form as nearly as possible an ac curate measure of time.

The impulses which make up for the natural resistance to the movement of the pendulum are derived from the elastic force of an impellingspring, I), fixed at I) upon the pendu tions of the fork constitute part of the circuit 1 lum-rod and tending to assume a position par= allel with the axis of the rod. The free end of the spring or a projection, If, therefrom enters between two projections, c c, 011 an armaturelevcr, d, pivoted to oscillate in a plane parallel with the plane of oscillation of the pendulum-rod a, and provided with an armature, d, between the opposite poles of two electromagnets, c c. 11' at the end of a vibration of the pendulum in one direction the armature lever (Z is moved so as to carry the projections c in the opposite direction, as shown in Fig. 1, the spring I) will be strained, and will tend to move the pendulum in the opposite direction to that in which it was last moving, and will thus provide the necessary impulse to keep up the movement of the pen dulum. In order to thus move or tilt the armature-lever (Z at the end of each vibration of the pendulum to thus strain the spring b for the next impulse, the circuit of the magnets 0 c is controlled by the movements of the pendulum, and the cores of one magnet are magnetized and of the other demagnetized at or near the end of each vibration of the pendulum. As shown, in this instance each magnet c c has two coils, which will for distinction be called the first and second. The first coil is in a permancntly-closed circuit, 2 3 t 5, for the magnet c, and 2 3 6 7 for the magnet c with the battery B. One terminal of each of the second coils is connected by wires 8 and 9, respectively, with one pole of the battery 13, and the other terminal of the second coil is connected, by wire 10 for the magnet c and wire 12 for the magnet c, with the projections c a, respectively, which are insulated from one another, and the other pole of the battery is connected by wire 13 with the pendulum-rod and spring I), so that when the said spring I) or its projection b" touches one or the other of the projections c or c the circuit is completed through both coils of the corresponding magnet, cor c, and at the same time the spring b is disconnected from the opposite projection, so that only one coil is in circuit in the other magnet, which is consequently energized and attracts the armature d with maximum ell'ect.

The parts are represented in Fig. 1 in the position assumed just after the pendulum in in its movement toward the left, as seen in the said figure, has brought the spring Z) into con tact with the projection 0, thus completing the circuit 2 18 b c 10 9 5 through the second coil of the magnet 0, so that the current passes through both coils of the said magnet, thus demagnetizing it, and just before the projection b had thus come into contact with the projection c it left the projection 0, thus breaking the circuit through the second coil of the magnet c, leaving the said magnet energized by the continuous current in its first coil, so that as soon as the magnet c was demagnetized, as just described, the unopposed attraction of the magnet c on the armature d moved the latter in the direction to press the projection 0 against the spring I), straining the latter, as shown, so that its elastic force in the effort to straighten or assume its normal condition acts upon the pendulum, impelling it toward the right. This impulse will continue during the movement of the pendulum until, finally, the spring will cease to bear on the projection c, and then in the farther movement of the pendulum, due to its momentum, the spring I) will become separated from the projection c, breaking the circuit of the see ond coil of the magnet 0, so that for a moment both magnets will be energized, but no movement will take place in the armature, as it is nearer the poles of the magnet e by which it was last attracted than to those of the magnet 0,- but immediately after, in the farther movement of the pendulum, the projection If will touch the projection 0, thus completing the circuit in the second coil of the magnet 0, thereby demagnetizing the said magnet and leaving the attractive force of the magnet 0 unbalanced, so that the armature (7. will be moved toward it again straining the spring I), as before described, but in the opposite direction, and the operations described will continue indefinitely as long as the battery supplies a current. The movements of the armaturelever (1 may also be used to turn the hands of the clock or indicate the time meas ured by the pendulum in any usual manner. As shown, the armaturelevcr is provided with an anchor, (1 having pallets d, which alternately engage the teeth of a whechf, shown as provided with thirty teeth and moving the space of half a tooth at each vibration of the pendulum and consequent vibration of the armature-lever, so that if the pendulum is of proper length to beat seconds the wheel f will turn once in a minute, and a hand or pointer, f, (see Fig. 2,) on the arbor f of said wheel will thus constitute a seconds-hand for the clock. The arborf ot' the wheel f may aetnate,'through suitable spced-reducing wheelwork, g, a minute-hand, g, which will make one complete revolution in an hour, and by additional wheel-work the hour-hand may be made to revolve once in twelve hours, the three hands being shown in this instance as concentric with one another, although it is obvious that, if desired, the secondshand might turn around a different axis from the other hands.

In order to actuate any number of clocks at different places in unison with the main clock thus far described, the wheel fmay be made to controlan electric circuit extending to the additional or secondary clocks, the mechanism of one of which is shown in Fig. 23,and consists, essentially, of an electro-magnet, m, in the circuit 20 21, including a battery, B, and a circuit-closer controlled by the main clock. The said circuit-closer consists of two springs, a, normally insulated from oneanother, and a pin, a, projecting from the wheel f, so that at one momentin therevolution of the said wheel ICO IIO

the pin will touch both springs and complete the circuit connected with them, thus energizing the magnets m of as many secondary clocks as may be included in the circuit 20 21. The armature m of the magnet m is then attracted, and its lever W is provided with a pawl, 0, which is then moved over one tooth of the wheel 1;, which has sixty teeth, and when the magnet on is subsequently demagnetized in the movement of the wheel f,which disconnects the pin a from the springs a, the retractor m will withdraw the armature m from the magnet, and in this movement the pawl 0 will turn the wheel 1) for the space of one tooth. The said pawl 0 is provided with an arm, 0, about at right angles to its line of action on the wheel p, and the movement of the said pawl under the action of the retractor is limited by a stop, 0 engaging the said arm 0, and thus limiting its movement, and at the same time forcing the end of the pawl in between the teeth of the wheel thus positively locking thelatter and preventing it from overthrowing or moving by its momentum beyond the point to which it is positively moved by the pawl. The retaining-pawl r prevents backward rotation of the wheel 1) when the actuatingpawl 0 is moved up to engage another tooth, and this latter movement of the pawl 0 is limited by a stop, at, for the armature-lever m so that the said pawl ocan move over only one tooth at a time, and the chance of a false movement of the wheel 1) is reduced to a minimum.

The arbor of the wheelp may be provided with a hand which will revolve once in an hour, and thus indicate, in connection with a suitable dial, the time to the nearest minute as measured by the main or primary clock, and the usual speed-reducing wheel-work will be employed to actuate an hour-hand for the said dial.

It is obvious that instead of using two electro-magnets, e e, in the main clock, a single magnet and retractor might be used; and instead of differential magnets ordinary magnets having a single coil might be used, the differential magnets being employed in order to prevent sparks at the circuit-closer controlled by the pendulum.

I claim- 1. The combination of a pendulum with an impelling-spring fixed at one end upon the pendulum-rod, and an electro-magnet, armature, and armature-lever which engages and strains the said spring, the spring forming apart of the circuit of the magnet and controlling its operation, substantially as described.

2. The pendulum and impelling device cooperatingtherewith, combined with an electro-magnet having two coils, one of which is in a permanently-closed circuit, and the otherof which is in a circuit controlled by the pendulum, and an armature for the said magnet, co-operating with the pendulum-impelling device, substantially as and for the purpose set forth.

3. The pendulum and impelling-spring W'itnesscs:

Jos. P. LIVERMORE, H. P. Barns. 

